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My S500 Europe version have check engine light ưith P0444 error code. P0444 mean purge control valve circuits open therefore the purge valve in permanent closed mode. However when I check the purge valve seem it still functioning properly as it should be: without 12v power then it closes and no air leak. If I open the valve but actuation menu on Star C4 then I realized that the valve is ticking open and closes via a ground signal provided by ECM and if I open the pipe connect to canister then I have vacuum leak from intake manifold, which mean that purge valve and control signal from ECU is normal as it should be but I don't know why error is set.
pipe to canister and canister are also inspected and they are not clogged. And for EVAP of Europe version, there is only purge control valve and it not equipped with 2nd valve on canister as US version. Do you know why error is set? Is this possible of purge valve is faulty due to aging and resistant increase over the time?
when I got mine in 2014 those two had been the ONLY software that was ever updated by Merc dealerships - BOTH should have been done during the original warranty period
just glanced to see if its clear why they did the update - I only found these bits form konigstiger's posts
Service Campaign 2007010008 FEB07, the software for the 722.9 transmission control module may need to be updated to adjust the lock up force of the torque converter. The engine control module will also be updated. Approximately 27,691 vehicles affected.
P-B-27.60/69a JUL08 (VIN A000355 to A016837) S550 uncomfortable downshifting while coasting resolved by reprogramming the engine control module.
Problem is solved after I swap purge valve with another car. Thing make me surprised is that both car working properly and no CEL after purge valve swap. I really don't understand what was wrong because before swap I did a bench test purge valve and do activation purge valve via Star C4 and system functions properly as it should be but CEL and error code are set.
